Single-shoe braking system



Dec. 3', 1968 SINGLE- l.. ToY 3,414,091

` SHOE BRAKING SYSTEM Filed April v2, 1965 2 Sheets-Sheet l l 50 F/6.f51

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ATTORNEY Dec. 3, 1968 l.. TROY 3,414,091

SINGLE-SHOE BRAKING SYS-TEMv BY MM ATTORNEY IN VENTOR United StatesPatent 3,414,091 SINGLE-SHOE BRAKING SYSTEM Leonard Troy, 611 N. WebsterAve., Scranton, Pa. 18510 Filed Apr. 2, 1965, Ser. No. 445,207 Claims.(Cl. 18S-78) This invention relates generally to new and usefulirnprovements in brake constructions, and is particularly practical foruse on trailer vehicles, i.e., trailer homes which are not moved toooften.

The brake assemblies generally used on home trailers which are normallyparked in a trailer camp site have been generally expensive andcomplicated. Since the relatively large trailer usually is permanentlyparked, the relatively complicated and expensive brake constructions areseldom used after the trailer home is permanently parked.

A primary object of the present invention is to provide a relativelyinexpensive brake construction of the singleshoe type.

Another object of the present invention is to provide a single-shoe typebrake construction in which the application of braking torque is appliedsubstantially in alignment with a wheel bearing whereby reduced bearingloads are encountered during a brake application.

Another object of the present invention is to provide a brakeconstruction in which a substantially open rotor provides optimumcooling during a brake application.

A further object of the present invention is to provide a simplemechanical brake construction which includes means for compensating forbrake shoe wear.

And yet another object of the present invention is to provide a novelbrake construction which is operated by means of a novel externalactuator.

These together with other and more specic objects and advantages willbecome apparent from the following description when taken in conjunctionwith the accompanying drawings, wherein:

FIGURE 1 is an elevation showing a portion of a Vehicle axle including awheel including the brake construction of the present invention,portions being broken away and shown in section;

FIGURE 2 is an enlarged view showing the brake drum of FIGURE 1;

FIGURE 3 is a side elevation taken substantially on the plane of line 33 of FIGURE 2;

FIGURE 4 is a section taken substantially on the plane of line 4 4 ofFIGURE 3 with components removed to illustrate details of the brakeconstruction;

FIGURE 5 is an enlarged perspective view of the bellcrank of the brakeconstruction with a portion broken away to show internal detailsthereof; and

FIGURE 6 is an elevation similar to FIGURE 3, showing an alternateembodiment of an adjustable link used to adjust shoe-to-drum clearances.

Referring to FIGURE 1, one-half of a vehicle axle is generallyillustrated and is indicated generally at 10. The axle 10 has dependingfrom a suitable bracket 12 a brake actuator 14.

The brake actuator 14 comprises a hollow, rigid housing 16 having asuitable inlet connection t-o which a vacuum line 18 is connected. Acontrolled source of vacuum (not shown) will communicate with the line18. The housing 16 will have suitably clamped thereto, resilient,dished-out diaphragms 20 at opposite sides thereof; only one being shownin detail. The diaphragms will function to operate the brakes atopposite ends of the axle. The diaphragms include a mounting wall 22which includes a rigid inner mounting plate 24. Sealingly connected tothe wall 22 and plate 24 by means of a nut-and-bolt assembly 26 is an3,414,091 Patented Dec. 3, 1968 "ice axially extending mounting bracket28 to which is connected, by a nut 30, the terminally threaded end of anelongated, force transmitting rod 32.

When a vacuum is introduced into the housing 16, the diaphragms 20 willmove toward the center line of the axle, accordingly moving the forcetransmitting rods sufciently to cause operation of the brakeconstruction to presently be described.

The axle 10 includes outer tapered ends 34 (only one shown) receiving onannular inner and outer lands 36 and 38, respectively, inner and outerannular bearing assemblies 40 and 42, respectively. A rotor 44 isjournaled on the bearings 40 and 42 by means of a retaining nut assembly46. The rotor 44 includes a circumferential m-ounting ange 48 upon whichis conventionally mounted a wheel-and-tire assembly 50. The rotor 44includes an inwardly-opening brake drum 52 having an annular brakingsurface 54 circumposed about the inner bearing assembly 40.

The annular braking surface 54 which substantially surrounds the bearingassembly 40 results in relatively little load or torque being applied tothe outer bearing 42 during a brake application. This arrangementresults in minimum wear on the bearing and eliminates the use ofoversized bearings.

The axle 10 hasxedly mounted thereon, within the space surrounded by thebraking surface 54, inwardly of the bearing 40, a mounting bracketindicated generally at 56; see FIGURE 3. The mounting bracket 56comprises a radially-extending support portion 58 to which is suitablypivotally mounted at 60 an arcuate brake Shoe 62 The brake shoe 62includes the usual brake lining 64 engageable with the braking surface54. The bracket 56 includes an upper, radially-extending fulcrum portion66 including a terminally-apertured end 68 to which is connected one end70 of a tension or brake-shoe return spring 72, the other end 74 of thespring being connected to an apertured inner ange portion 76 of thebrake sh-oe 62. The inner flange of the brake shoe 62 includes aninwardly opening bearing or socket portion 78, the function of which tobe subsequently described in detail.

The fulcrum portion 66 includes a pair of spaced, arcuate bearing lips80 and 82 in substantially aligned relation, and disposed on oppositesides of an inverted U-shaped notch 84; see FIGURES 2-4 and 6.

Indicated generally at 86; see FIGURES l5, is a bellcrank comprisingopposed bearing or fulcrum portions 88 and 90 disposed on opposite sidesof an arcuate housing 92. The housing extends substantially through aninety degree arc and has an internal pivot socket portion 94. Thehousing 92 is oiset with respect to the general plane of a dependinglever portion 96 including a lower, transversely apertured, bifurcatedend 98. AA pivot pin 100 extends transversely through the end 98 of thelever 96 and has engaged thereon the terminal hook end 102 of the forcetransmitting rod 32.

An adjustable push rod, indicated generally at 104, extends between thepivot socket portion 94 and recessed portion 106 of socket portion 78;see FIGURES 2 and 3, disposed in opposed relation to the socket portion9'4.

The push rod 104 includes a generally hemispherical upper bearing end108, an intermediate wrench-receiving portion 110 having a polygonalcross-section, and a lower threaded end 112. A lock nut 114 is threadedonto an intermediate portion of the threaded end 112, and the threadedend 112 is received into the internally threaded bore 116 of an abutmentnut 118 which includes an axial abutment shaft having a hemisphericalend received in the recess 106. The abutment nut 118 includes an upperpolygonal cross-section to accommodate a wrench thereon.

The push rod 104 may be adjusted in length to adjust for shoe-to-drumclearance when the brake shoe is in a normal or retracted condition dueto the force exerted by tension spring 72, i.e., draws shoe lining 64away from the inner surface 54 of drum 52. Wear 0n the lining 64 may becompensated for by the extension of push rod 104.

Adjustments are made by backing off lock nut 114, threading end 112 intoor out of the bore 116, and nally running the lock nut 114 back intoengagement with abutment nut 118 after the proper brake-shoe-to-drumclearance is obtained.

Considering FIGURE 6, parts similar to those of FIG- URES lare identiedby reference numerals which have been previously used.

The brake shoe is indicated at 62 and includes a modied socket portion78' which is internally threaded at 116'.

A modified push rod is indicated generally at 104 and includes a rodelement 110 which includes upper and lower hemispherical ends. A lowerabutment nut 118 is externally threaded at 112 and is received in thethreaded bore 116', A lock nut 114 is threaded on an intermediateportion of the external threads 112 and will clampingly engage thesocket portion 78'. The nut 118) includes an upper polygonal portion toreceive a wrench thereon, and an internal recess 106 to receive thelower hemispherical end of rod element 110'.

Adjust-ments are made by backing off the lock nut 114 and rotating nut118 in threaded bore 116' and thus the push rod 104' functions in thesame manner as push rod 104.

Operation Considering FIGURE l, when the interior of the housing 16 iscommunicated with a vacuum by suitable control means (not shown), thediaphragms 20 move inwardly (there is one for the wheel brake assemblyat each end of the axle resulting in the force transmitting rod movingtoward the center line of the vehicle.

The brake shoe-to-drum clearances will have been adjusted by means ofthe push rods 104 and 104 as previously described.

The movement of the rod 32 toward the left, as seen in FIGURE 1, resultsin pivoting the bellcrank S6 on the fulcrum portion 66 of the bracket56. Pivoting of the bellcrank to the left, as seen in FIGURE 2, causesthe bellcrank socket portion 94 of the bellcrank housing 92 to reactagainst the upper end of the push rods 104 and 104, and urge the brakeshoe 62 about its pivot 60* at the socket portions 78 or 78',respectively, into engagement with the braking surface 54 of the drum orrotor 52.

The braking action mentioned above occurs against the force normallyimposed by the tension or return spring 72. Communication of atmosphericpressure to the interior of housing 16 eliminates the tension on rod 32and permits the return spring 72 to pivot the brake shoes away from thebraking surface.

Briey in review, the following functions and advantages are afforded bythe system and structure of the invention:

(1) The brake drum 52 opens inwardly and since no internal actuators arepresent within the drum, heat is rapidly dissipated to aid in reducingbrake fade during panic stops, for example;

(2) The application of braking force in substantially a plane includingthe inner wheel bearing 40 and this substantial planar alignment aids toreduce bearing wea-r and permits minimum sized bearings to be used',

(3) The number of parts used in the brake assembly is reduced to aminimum thus facilitating installation, maintenance and repair;

(4) Adjustment of brake shoe-to-drum clearances is simple and expedient;

(5) The brake shoe and cooperating braking surface can be of aconsiderable width as compared with a conventional brake assembly, andthus a single shoe installation is practical for vehicles such as housetrailers, for example, when the brakes are normally used only when thetrailer is transported to a relatively permanent parking site;

(6) The installation lends itself to operation by an external actuator,preferably vacuum operated, from the conventional source found ontractors `or other conventional draft vehicles; and

(7) Dust shields may be utilized or omitted with the open brake drum,depending upon the customers preference.

What is claimed is:

1. In a vehicle brake system, an axle, a brake drum journaled on the endof said axle and including an annular brake surface, said brake drumopening away from the end of said axle, and at least one brake shoeassembly mounted on said axle within said brake drum, said brake shoeassembly comprising a bracket mounted on said axle and including asupport portion and a fulcrum portion extending radially from said axle,an arcuate brake shoe pivotally engaged at one end to said supportportion on a pivot axis spaced from said axle, spring means connected`between the other end of said brake shoe and said bracket for normallyurging said brake shoe away from said annular braking surface of saiddrum, said fulcrum portion including bearing lip means disposed inopposed relation to an intermediate portion of said brake shoe remotefrom the pivot axis thereof, bell crank means engaged with said bearinglip means and including a lever portion extending toward the other endof said brake shoe and including a portion for connection to a forcetransmitting rod, said bell crank means including a socket portionopening toward said brake shoe, said Drake shoe including a socketportion opening toward the socket portion of said bell crank means, andpush rod means abuttingly engaged between socket portions of said bellcrank means and said brake shoe whereby pivotal movement of said bellcrank means on said bearing lip means by movement of said bell crankmeans lever portion in the direction toward which said brake drum openscauses said brake shoe to be urged into engagement with said annularbraking surface against the force imposed by said spring means.

2. In a vehicle brake system, an axle, a brake drum journaled on theterminal end of said axle and including an annular brake surface, saidbrake drum being substantially open at the side opposite the terminalend of said axle, and at least one brake shoe assembly mounted on saidaxle within the space defined by planes normal to said axle and passingthrough outer margins of said annular braking surface, said brake shoeassembly comprising a bracket mounted on said axle and including asupport portion and a fulcrum portion extending radially from said axle,an arcuate brake shoe pivotally connected at one end to said supportportion on a pivot axis parallel to said axle, tension spring meansanchored between the other end of said brake shoe and said bracket fornormally urging said brake shoe away from said annular braking surfaceof said drum, said fulcrum portion including bearing lip means disposedin opposed relation to an intermediate portion of said brake shoe remotefrom the pivot axis thereof, a bellcrank abuttingly engaged at one endwith said bearing lip means and including a depending lever portionextending toward said other end of said brake shoe and including aconnecting portion for connection to an external force transmitting rod,said bellcrank including a socket portion opening toward said brakeshoe, said brake shoe including a socket portion opening toward saidinternal socket portion of said bellcrank, and a push rod abuttinglyengaged on respective opposite ends between said socket portion of saidbellcrank and said socket portion of said brake shoe whereby pivotalmovement of said bellcrank on said lip means by movement of saidbellcrank lever portion toward said open side of said brake drum causessaid brake shoe to be urged into engagement With said annular brakingsurface against the force imposed by said tension spring means.

3. The structure as claimed in claim 2 in which said push rod includesmeans thereon adjusting the eiective length thereof to adjust `brakeshoe-to-drum clearances.

4. The structure as claimed in claim 2 including a bearing assemblycircumposed about said axle between said brake drum and said axle anddisposed within the area dened by said planes normal to the outermargins of said annular braking surface and in substantial planaralignment with said brake shoes.

5. The structure as claimed in claim 2 in which said bearing lip meanscomprises a pair of spaced, substantially colinear, lip portionsdisposed on opposite sides, a notch portion in said mounting bracketfulcrum portion, said bellcrank including a housing in which saidinternal References Cited UNITED STATES PATENTS 2,320,191 5/1943 Mott92-50 2,538,232 -1/1951 Bowe 188--78 2,684,131 7/1954 Buttereld 18S-783,135,362 6/1964 Troy 188-78 MILTON BUCHLER, Primary Examiner.

T. W. BUCKMAN, Assistant Examiner.

1. IN A VEHICLE BRAKE SYSTEM, AN AXLE, A BRAKE DRUM JOURNALED ON THE ENDOF SAID AXLE AND INCLUDING AN ANNULAR BRAKE SURFACE, SAID BRAKE DRUMOPENING AWAY FROM THE END OF SAID AXLE, AND AT LEAST ONE BRAKE SHOEASSEMBLY MOUNTED ON SAID AXLE WITHIN SAID BRAKE DRUM, SAID BRAKE SHOEASSEMBLY COMPRISING A BRACKET MOUNTED ON SAID AXLE AND INCLUDING ASUPPORT PORTION AND A FULCRUM PORTION EXTENDING RADIALLY FROM SAID AXLE,AN ARCUATE BRAKE SHOE PIVOTALLY ENGAGED AT ONE END TO SAID SUPPORTPORTION ON A PIVOT AXIS SPACED FROM SAID AXLE, SPRING MEANS CONNECTEDBETWEEN THE OTHER END OF SAID BRAKE SHOE AND SAID BRACKET FOR NORMALLYURGING SAID BRAKE SHOE AWAY FROM SAID ANNULAR BRAKING SURFACE OF SAIDDRUM, SAID FULCRUM PORTION INCLUDING BEARING LIP MEANS DISPOSED INOPPOSED RELATION TO AN INTERMEDIATE PORTION OF SAID BRAKE SHOE REMOTEFROM THE PIVOT AXIS THEREOF, BELL CRANK MEANS ENGAGED WITH SAID BEARINGLIP MEANS AND INCLUDING A LEVER PORTION EXTENDING TOWARD THE OTHER ENDOF SAID BRAKE SHOE AND INCLUDING A PORTION FOR CONNECTION TO A FORCETRANSMITTING ROD, SAID BELL CRANK MEANS INCLUDING A SOCKET PORTTIONOPENING TOWARD SAID BRAKE SHOE, SAID BRAKE SHOE INCLUDING A SOCKETPORTION OPENING TOWARD THE SOCKET PORTION OF SAID BELL CRANK MEANS, ANDPUSH ROD MEANS ABUTTINGLY ENGAGED BETWEEN SOCKET PORTIONS OF SAID BELLCRANK MEANS AND SAID BRAKE SHOE WHEREBY PIVOTAL MOVEMENT OF SAID BELLCRANK MEANS ON SAID BEARING LIP MEANS BY MOVEMENT OF SAID BELL CRANKMEANS LEVER PORTION IN THE DIRECTION TOWARD WHICH SAID BRAKE DRUM OPENSCAUSES SAID BRAKE SHOE TO BE URGED INTO ENGAGEMENT WITH SAID ANNULARBRAKING SURFACE AGAINST THE FORCE IMPOSED BY SAID SPRING MEANS.